Spreader stoker fuel feeding mechanism



Nv. l, 1949. D. J. MossHART ETAL 2,486,570

SPREADER STOKER FUEL FEEDING MECHANISM Filed Oct. 18, 1946 28 ZwlTNEssEs: Z a INVENTOR s M Down/ D :JI Moss/HART. /E 2 :fof/N .5.HsRw/CK.

ATTORNEY Patented Nov. l, 1:949

SPREADER STOKER FUEL FEEDING MECHANISM Donald J. Mosshart, Ardmore, andJohn S. Herwick, Philadelphia, Pa., assignors to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of PennsylvaniaApplication October 18, 1946, Serial No. 704,160

4 Claims. (Cl. 110-115) This invention relates to stokers, moreparticularly to those of the spreader or sprinkler type, and has for anobject to provide improved apparatus of this character.

In spreader stoker apparatus, where the fuel is fed rearwardly over thedischarge end of a spill plate, for gravitational feed to impellermechanism, the fuel so fed frequently falls in large masses or chunksfrom the rear end of the spill plate to the impeller therebelow. Thiscondition is aggravated when the fuel is wet, and even With dry fuel thefuel falls from the spill plate in sufficiently uneven quantities and atsuch uneven rates that the feeding thereof by the impeller to theinterior of the furnace is generally erratic. Where the fuel fallsuniformly from the spill plate to the impeller, the impact between theimpeller and the fuel is substantially uniform, but where the fuel fallsin irregular or small masses there is a cushioning effect resulting innon-uniform distribution of the fuel by the impeller.

In lcopending application, Serial No. 504,395, for Spreader stokermechanism, led September 30, 1943, now Patent No. 2,423,110 granted July1, 1947, and assigned to the assignee of the present invention, there isdisclosed apparatus for overcoming this difficulty and which apparatusinvolves a corrugated plate extending transversely of the spreadermechanism, with the corrugations extending vertically, the plate beingso disposed that reciprocation thereof causes the ribs of thecorrugations to rub upon the fuel as the latter approaches the dischargeend of the spill plate, thereby reducing the size of the mass of fuel bya grating or shredding action, the grated or shredded particles of fuelfalling uniformly to the impeller therebelow.

It has been found that, under certain conditions, this equalizing plate,which is mounted for pivotal movement about a horizontal axis so thatthe lower edge thereof may be forced away from the spill plate reardischarge edge by the fuel pushing thereagainst, is sometimes pushedaway from the spill plate by a large lump of coal or foreign matterwhich opens a gap between the equalizer plate and rear discharge edgethrough which an excessive quantity of fuel may cascade to the impellertherebelow. Also, where a plurality of rams or equivalent structures areoperating out of phase to push fuel rearwardly over the spill plate andagainst the equalizing plate, the action of the rearmost ram may swingthe equalizing plate away from the rear discharge edge` of the spillplate thereby opening an excessive gap all along the spill plate rearedge, resulting in an undesirable cascading of fuel to the impeller.

The present invention eliminates this difficulty by providing anequalizing plate structure in which a plurality of plate elements aremounted on a horizontal axis for independent pivotal movementthereablout so that any one plate element can move away from the rearspill plate discharge edge and the remaining plate sections remain`adjacent thereto. Preferably, the plate elements correspond intransverse location to the fuel-pushing rams, paddle wheels or othermechanisms for feeding the fuel from the hopper to the rear spill platedischarge edge.

Accordingly, another object )of the invention is to provide, in spreaderstoker apparatus, means for effecting a uniform feed of fuel to theimpelling structure.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing, forminga part of this application, inwhich:

Fig. 1 is a longitudinal sectional view through spreader stokerapparatus embodying the principles of the present invention; and,

Fig. 2 is a transverse sectional view taken along the line II-II of Fig.1, looking in the direction indicated by the arrows. Y

Referring now to thek `drawing more in detail, the reference characterI0 indicates, in its entirety, spreader mechanism for feeding fuelrearwardly through the opening I I inthe front Wall I2 of the furnaceI3, for distribution thereof on the gratestructure I4, at the bottom ofthe furnace. Fuel is fed by gravity fromthe hopper I6 to the bottomplate I'I of the ram box structure I8 where a pair of rams I9, disposedin side-byside relation, push the fuel rearwardly. The rams I9 may bereciprocated by any suitable mechanism (not shown) and which derives itspower rfrom the engine 20 (Fig. l). Preferably, the ram-reciprocatingmechanism is so arranged that the two rams I9 operate out -of phase byapproximately l degrees with the result that while one ram is movingrearward the other ram is moving forward.

Reciprocation of the rams I9 pushes the fuel from the hopper I 6rearwardly over the spill plate 23 for gravitational discharge over therear edge 2'4 thereof to the rotary impeller 26 positioned therebelow.The impeller 26 is mounted on a horizontal shaft 21 and carries aplurality of blades 28 adapted to strike the fuel falling from 3 therear discharge edge of the spill plate and to project it rearwardlythrough the furnace wall opening H to the grate structure I4.

In order to vary the trajectories of the fuel leaving the rotaryimpeller 26, the spill plate preferably is arranged for longitudinalreciprocation, such movement being imparted thereto by rods 29, 4links30 and cranks 3|, the latter being xed on the shaft 32 Which may beoscillated in any desired manner, one such means being fully disclosedin copending application, Serial No. 549,848, filed August 17, 1944 andassigned to the assignee of the present application.

The equalizing mechanism, indicated in its entirety by the referencecharacter 35, for preventing lcascading of large quantities of fuel fromthe rear discharge edge 24 of the spill plate, includes a pair of platemembers 36 pivotally mounted at their upper edges on a horizontaltransversely-extending shaft 31 with the lower edges 36 of the platesdisposed close to the spill plate rear discharge edge 24.` The hollowbeads 39 at the upper edge of the plates 36, through which the shaft 31passes, project laterally beyond the side wal-1s 4| of the spreadercasing, as at 42, with arms 43 rigidly secured to the projectingportions 42.

A pair of wires 44 are connected at one end, through turn-bucklestructures 45, with the free ends of the arms 43, these wires 44 passingaround a pair of pulleys 46 carried by brackets 41 secured to the angleiron 43 on the furnace front wall l2. The other ends of the wires 44 aresecured to opposite ends of the tension spring 49 which results inforces being applied to the two plate sections 36 which forces urge theplate lower edges 38 into contact with the rear discharge edge 24 of thespill plate 23.

It will be apparent that, if either plate section 36 is swung rearwardlydue to the pushing action thereagainst of fuel moved rearwardly by theram aligned therewith, the corresponding end of the wire 44 will bepulled forwardly through the turn-buckle mechanism 45, therebyincreasing the tension in the spring 43 which in turn will increase theforce upon the other plate section 36 urging it even more` firmly intoengagement with the rear discharge edge 24 of the spill plate, therebypreventing accidental cascading of excessive quantities of fuel past theother plate section 36 upon rearward movement of the first platesection.

As in the construction disclosed in the rstmentioned copendingapplication, means are provided for transversely reciprocating theequalizing plate structure to impart a shredding or grating action tothe fuel pushed thereagainst by the rams. In the present construction,this reciprocating mechanism comprises extensions I on the horizontalshaft 31 which supports the equalizer plate sections 36. Theseextensions 5l are supported by pairs of vertically-spaced rollers `52carried by brackets 53 and 54. Limited reciprocating movement of theshaft 31 is eected by lever 55 and links 56 and 51, the link 56connecting the upper end of the lever 55 to one end of the shaft 31 andlink 5lconnecting the lower end of the lever 55 to an eccentric 58.carried by the output shaft of a gear box 59 whose input shaft pulley6| is driven by the belt 62, through the pulley 63 on the rotaryimpeller shaft 21, which may be driven from any suitable source (notshown).

To avoid any possibility of breakage of thereciprocating mechanism dueto jamming of the y spill plate sections 36, the pivot 64 of the leveris carried by a support 65 which floats between a pair of opposed coilsprings 66, as shown at the left of Fig. 2.

Preferably, vertical ribs 61 are provided on the forward face of theequalizer plate sections 36 to increase the grating action of thereciprocating plate sections on the fuel pushed thereagainst by the ramsI9.

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various changes and modifications without departing fromthe spirit thereof.

What is claimed is:

l. Spreader stoker mechanism comprising an impeller; fuel-supportingstructure having a rear discharge edge positioned for gravity feed offuel therefrom to said impeller; means for feeding fuel rearwardly alongthe fuel-supporting structure to the rear discharge edge thereof; a pairof plates disposed 'adjacent the fuel-supporting structure reardischarge edge and adapted for pivotal movement relative to a horizontalaxis parallel to said rear discharge edge; and means iasing said platestowards engagement with said rear discharge edge, said last-mentionedmeans including mechanism Ifor increasing the biasing force on either ofsaid plates when the other plate is moved against its biasing force.

2. Spreader Stoker mechanism comprising a fuel impeller; structureproviding a fuel-supporting surface having a rear discharge edgepositioned for gravitational feed of fuel therefrom to said impeller;means for feeding fuel rearwardly along said fuel-supporting surface tosaid rear discharge edge; wall structure including a pair ofvertically-extending sections mounted for independent pivotal movementabout an axis above and approximately parallel to said rear dischargeedge; and an energy-storing device connected with both of said wallsections for continuously exerting on said sections forces tending topivot the latter into positions retarding gravitational discharge offuel from the fuel-supporting surface rear discharge edge, movement ofeither section away from discharge-retarding position effecting increasein the force exerted on the other section by the energy-storing device.

3. Structure as specified in claim 2, wherein the energy-storingdeviceincludes a tensioned spring with @opposite ends connected to thetwo wall sections whereby movement of either of the wall sections awayfrom fuel-discharge-retarding position effects increasein the tension ofthe spring with consequent increase in the force exerted fon the othersection by said spring.

4. Spreader Stoker mechanism comprising a fuel impeller; structureproviding a fuel-supporting surface having a rear discharge edgepositioned for gravitational feed of fuel therefrom to said impeller; apair of first members for feeding fuel rearwardly along saidfuel-supporting `surface in a pair of parallel paths with one of saidrst members lagging the other in fuelfeeding action; a pair of barriermembers each mounted for movement independent of the other toward andaway from said rear discharge edge within predeterminedlimits inresponse to pushing action of the respective streams of fuelthereagainst, said barrier members normally being positioned in closeproximity to said rear discharge edge and across the parallel paths offuel feed, and means responsive to movement of either of the-barriermembers away from the fuel-support- DONALD J. MOSSHART. JOHN S. HERWICK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,163,825 Bros June 27, 19392,423,110 Mosshaxt July 1, 1947

